Just Married ... With Children - S2-E20
Factual error: In the game show near the end, when Marcy and Steve come out as Al and Peggy. When the real Al and Peggy win the car, because they used Marcy and Steve's names, the car would have never gone to the real Al and Peggy. In reality, it would have gone to Steve and Marcy because it was won under their names. Al and Peggy would not have been able to keep the car. In fact Al and Peggy would not have been allowed to be on the show at all using someone else's name.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.